99 golf P0171 trouble code Bank 1 too lean

[orlie]

Having a problem finding what is wrong with my fuel. Trouble code comes up P0171 Fuel system too lean Bank 1. Can you help?

[boschmann]

That code sets because the engine computer can no longer correct the air/fuel mixture & it is on it's lean limit (cannot make mixture any leaner). Usually this is a symptom of a bad mass air flow sensor (out of calibration). The only way to verify this is to have a VAG scanner or simulator & look at certain measuring blocks. Sometimes you can see it on a generic scanner's datastream as excessive fuel trim values & unbelievable values coming from the MAF, other times it can be more subtle. Your other option is to just replace the MAF as they have dropped significantly in price, due to their frequent failure rate. They are fairly simple to replace, right on the air filter housing. Any place like Autozone can then reset your check engine light.

[veedubmechanic]

vw has issued an extended warranty for maf sensors on 99-01 new body style. its 7yr 70,000 miles. If you're car has less than 70k miles then you can get it replaced for free. This code is also set if you have any vacuum leaks. sometimes the code is also set if the front O2 sensor is faulty.